Sirtuin

Sirtuins are a conserved family of NAD⁺-dependent deacylases and class III histone deacetylases that couple cellular energy status to transcriptional and metabolic regulation, thereby influencing stress adaptation, genome maintenance, and cellular homeostasis^[1][2]. Mechanistically, sirtuins respond to fluctuations in NAD⁺ availability and regulate pathways associated with oxidative stress resistance, mitochondrial function, DNA repair, and metabolic efficiency through deacylation of histone and non-histone protein targets^[2][3][4]. These activities place sirtuins at the intersection of nutrient sensing and cellular responses to environmental and physiological perturbations, including fasting, caloric restriction, DNA damage, and redox imbalance^[2][4]. In disease-relevant contexts and experimental models, altered sirtuin activity has been linked to aging-related functional decline, metabolic disorders, inflammation, and impaired mitochondrial homeostasis, making the family an important framework for mechanistic studies of age-associated pathophysiology^[2][5]. Compared with related isoforms, mammalian SIRT1-SIRT7 display distinct subcellular localization and biological functions, with SIRT1, SIRT6, and SIRT7 enriched mainly in the nucleus, SIRT2 primarily localized in the cytoplasm, and SIRT3, SIRT4, and SIRT5 concentrated in mitochondria, supporting isoform-specific regulation of cellular processes^[1][3]. For experimental applications, sirtuin-modulating compounds, including sirtuin-activating compounds and inhibitors such as nicotinamide, are widely used to investigate NAD⁺-dependent signaling networks and the contribution of individual sirtuin isoforms to metabolism, aging, and disease mechanisms^[5][6].